This invention relates to floating dredges of the type having pontoons mounting a superstructure including supports for a gantry. A trolley rides on tracks on the gantry to position a bucket grab connected to the trolley. The bucket grab removes sand, clay, gravel or the like from the bottom of a waterway. A material handling apparatus is provided on the pontoons to receive and process the dredged material.
The dredged material sometimes will contain components whose value justifies recovering them. Sand and gravel are examples. Other components such as clay are not desirable for recovery and are simply collected for removal. Separating the recoverable material from the unrecoverable, however, slows down the dredging process. This is because in the past all dredged material has had to be processed through the material handling apparatus even when it contained nothing of value.